Screen
Printing Overview:
Screen printing, also called silk screening, is a way to print
custom or personalized logos, text, or artwork repeatedly on
t-shirts, sweatshirts, koozies, bags or any other apparel you
wish to customize. Basically, a screen is imprinted with your
design, placed over the item to be printed, and then ink is
forced through the screen with a squeegee onto the item. The
item is then place through an oven to cure the ink.
Screen
Printing Process:
We decided to explain the process of screen printing to help
you understand the steps it takes to create your custom screen
printed t-shirts.
Step 1 Artwork:
Artwork is either sent to us from the customer or we create
it from the customer’s idea. We prefer to use or create
vector type files because it provides nice sharp images no
mater what size is used.
Once we
have the artwork, we generate t-shirt composites, that we
place on our website, for the customer to review and approve.
This is not an actual printed t-shirt but a computer generated
t-shirt, which will be a really good representation of what
the artwork will look like and shows placement of the artwork.
The customer is required to approve this t-shirt composite
before we go to the next step. At this time you can instruct
to make any changes. We'll work with you until you are 100%
satisfied with the design!
Once the artwork is approved we print the design as a positive
on a transparency. If the design has more than one color,
we have to separate the design and print a positive for each
color so that we can create a separate screen for each one.
Step
2 Screen Preparation:
The screens that we use are mounted on a wooden frame and
there are different screen mesh sizes. The mesh size to use
is determined by the detail of the artwork. The more fine
line detail, the higher the mesh count screen is required.
The screen has to be prepped by cleaning with screen wash
and then with a degreaser. The screen is then dried. Once
the screen is dried it has to be coated with a photosensitive
emulsion. This has to be applied under yellow light because
any exposure to UV light will activate the emulsion and render
it useless. The screen is placed in a dark drying cabinet
so the emulsion can dry.
Step 3 Screen Exposure:
Once the emulsion has dried the positive film transparency
is temporarily taped to the backside of the screen. It is
positioned according to how it will appear on the t-shirt.
Then the screen is placed into the exposure unit. The exposure
unit shines UV light on the screen, which exposes the photosensitive
emulsion that is not being blocked by the artwork on the transparency.
Once exposed, the screen is placed in the wash-out tub and
the screen is sprayed with high pressure water. The emulsion
that was blocked out by the artwork washes away with water.
The emulsion that was exposed to the UV light is now chemically
bonded to the screen and does not wash out with water. So
after spraying the screen, the only openings on the screen,
is the artwork image. If there is more than one color you
do this for each screen.
Step
4 Screen Printing Process:
After the screen dries, the screen must be blocked by taping
the border of the screen and any unwanted openings. Pinholes
are filled in using a block-out pen. This process is repeated
for all screens.
The screen is then placed on the press. There are several
types and sizes of presses; we use a 4-platen 6-color manual
press. This means we are capable of printing designs with
6 colors and the ink is applied manually. The screen is clamped
in the press and aligned so that the image will print in the
correct place on the t-shirt. If there is more than one color
then there is a screen for each color and they have to be
placed on the press and each one is aligned with the other
screen so that when the ink is applied, each color is in the
correct position. The alignment is done with registration
marks and a careful eye.
Once the screen or screens are on the press, now it’s
time to apply the ink. The ink is plastisol ink and we use
Union ink for it’s excellent quality. The specific color
of ink is spread along the base of the screen or screens.
A squeegee is used to apply the ink. The t-shirt is placed
on the platen. The screen is put into position above the platen.
To apply the ink, we first have to flood the screen with the
ink by pulling a thin coat of ink across the top of the screen
with the squeegee. The screen is then lowered down over the
t-shirt. We use the squeegee to push the ink through the screen
onto the t-shirt. The press is designed so that the screen
is always in alignment with the platen, therefore you can
be sure the screen is always in the same position. So if you
are doing more than one color, the t-shirt remains on the
platen, the next screen is rotated over the platen and the
new ink color is applied to the t-shirt. This process is repeated
for every color of the design. Sometimes, in order to print
one color over top of another color, it may be necessary to
flash the previous ink on the t-shirt. To flash, the platen
is rotated under the flash unit, which is a heater the size
of the platen. The flash unit will heat the ink very quickly,
in a matter of a few seconds, so that it gels over, which
allow you to print the next ink directly over top. This is
important especially when doing an underbase that all other
ink colors are printed directly on. Once all colors have been
applied, the t-shirt is removed from the platen and put through
the conveyor dryer oven. Plastisol type ink only cures with
heat, so the t-shirt has to be heated to at least 300°F
to set the ink. The t-shirt is finished when it comes out
of the oven, unless there is another design being printed
on the opposite side and / or sleeve, then the screen printing
process is repeated. This process is the same for printing
on t-shirts, sweatshirts, fleece wear, koozies, bags or other
apparel.
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